Hydrogen storage without high pressure tanks, but in a liquid with baking soda!

Here’s how it works: Solutions of formate ions (hydrogen and carbon dioxide) in water carry hydrogen based on non-corrosive alkali metal formate. The ions react with water in the presence of a catalyst. That reaction makes hydrogen and bicarbonates the “baking soda” Autrey admires for its absence of environmental impacts. With the right mild tweaks in pressure, the bicarbonate-formate cycle can be reversed. That provides an on-off switch for an aqueous solution that can alternately store or release hydrogen. Before baking soda, the PNNL hydrogen storage team looked at ethanol as a liquid organic hydrogen carrier, the industry’s blanket term for storage and transport media. In tandem, they developed a catalyst that releases the hydrogen. Catalysts are designer additives that speed the processes used to make and break chemical bonds in an energy-efficient way. In May 2023, for a project related to the PNNL effort, EERE granted OCOchem of Richland, Washington, $2.5 million in funding over two years to develop an electrochemical process that makes formate and formic acid from carbon dioxide. The process would bind carbon dioxide with the hydrogen located in water’s iconic chemical bond, H2O. In a partnership just starting, PNNL will develop ways to release hydrogen from the OCOchem products. Hydrogen storage that ‘looks like water’ In the world of hydrogen storage research, the bicarbonate-formate cycle has created a buzz for quite some time. After all, it is based on materials that are abundant, non-flammable, and non-toxic. The cycle is built on an aqueous storage solution so mild it “looks like water,” said Autrey. “You can put out a fire with it.” But for formate-bicarbonate salts to become a viable means of storing hydrogen energy, researchers must still develop economically feasible scenarios. So far, the technology stores hydrogen at only 20 kilograms per cubic meter, compared to liquid hydrogen’s industry standard of 70. More fundamentally, said Autrey, researchers need a systems-level understanding of the required electrochemistry and catalysis. In engineering terms, to date, the idea of a workable bicarbonate-formate cycle has a low technical readiness level. “If we solve the catalysis problems,” he added, “we could get some real interest.” ‘An amazing shiny thing’ On the plus side, the salt solutions under consideration at PNNL release hydrogen upon reaction with water. They also operate at moderate temperatures and low pressures. In theory, at least, as Autrey and Gutiérrez describe in their 2023 paper, the bicarbonate-formate cycle represents “a feasible green alternative for storing and transporting energy” from hydrogen. The baking soda idea is also at the nexus of what the 2023 paper calls “several urgent scientific challenges.” Among them are how to make a hydrogen storage media from captured excess carbon dioxide. And even to use the same media to store electrons, which offers the promise of direct formate fuel cells. In addition, the PNNL work could provide insights for catalysis in the aqueous (water) phase. For now, the PNNL team is using palladium as their candidate catalyst. Their efforts include finding ways to make the rare metal more stable, reusable, and longer-lived. All in all, the baking soda idea “is this amazing shiny thing” for hydrogen storage, said Autrey. “What’s exciting are the possibilities.” *** https://oilprice.com/Energy/Energy-General/Simple-Kitchen-Ingredient-Might-Revolutionize-Hydrogen-Storage.html